Translating apparatus



Dec. 27, 1927.

1,654,062 F. c. WILLIS TRANSLATING APPARATUS Filed May 14, 1923 III Patented Dec. 27, 1927.

UNITED STATES PATENT OFFICE.

FREDERICK C. WILLIS. OF WEST NE\V BRIGHTON, NEXV YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, U. S. A., A CORPORATION OF NEW YORK.

This invention relates to translating apparatus, and more particularly to modulators employed in carrier current and radio signaling systems.

Certain objects of the invention are to provide a more ellicient modulator; to pro vide a modulator wherein less energy of carrier frequency is required to maintain the control electrode at the optimum potential for modulating purposes; to provide a balanced modulator of the electronic valve type 'wherein the control electrodes thereof are maintained at the proper potential with small input energy of carrier frequency; to provide a modulator wherein the full force of the source of high frequency carrier oscillations is applied to the control electrode thereof.

Modulators of the electronic valve type with only a single valve or two valves in balanced relation are employed in carrier current telegraph and telephone systems and in radio systems. Speech frequency currents, telegraph currents or other signaling currents impressed upon the modulator interact therein with high frequency current-s supplied thereto and produce modulated high frequency currents.

The modulating currents ordinarily originate on a line coupled to the modulator input circuit through a transformer.

In order to prevent fluctuations of the ca pacity between the windings of such a trans former anc ground, the core and containing case of the transformer are grounded. In practice, one terminal of the heated cathode of such an electronic modulator is also grounded to prevent fluctuations in the ca pacity between the parts of the modulator and ground.

As heretofore employed, the source of carrier frequency currents has been coupled to the modulator input circuit between the heated cathode and the modulating current input transformer or other coupling.

It has been found that the capacity between the modulating current input coupling and ground, and the capacity from the incoming line and the apparatus thereof to ground shunts the carrier frequency cur rents from the control electrode of the mod ulator ecessitating a greater amount of iu put energy to maintain the control electrode at the optimum potential.

TRANSLATING APPARATUS.

Serial No. 638,750.

This shunting effect increases With increase in the frequency of the carrier currents, so that in high frequency carrier and radio systems, an abnormal amount of input energy is required.

In accordance with the present invention the apparatus of the modulator input circult is so organized and the carrier frequency source is so coupled thereto that such capacity to ground has no effect upon the potential of the control electrode.

The invention is illustrated as applied to a modulator having two electronic valves connected in balanced relation, but it is to be understood that it may be applied to other types of modulators and employed in other relations.

Referring to the drawing, a pair of threeelectrode electronic valves 1 and 2, each having a grounded cathode or filament heated by current from a battery or other source, an anode or plate, and control electrode or grid, are provided. The valves are preferably similar and equal in their structure and characteristics.

The input circuits of the valves are urranged in parallel with respect to the secondary Winding of a transformer 3 in the common conductor of the two input circuits. The primary of the transformer 3 is connected in circuit with a source 4 of high frequency oscillations. One terminal of the transformer secondary is connected to the cathodes of the valves 1 and 2, and the other terminal thereof to the rotor of a balancing variable condenser 5. The stators of the condenser are connected to the respective conductors individual to the valve input circuits.

Condenser 5 is made variable so that the impedance of the individual paths of the input circuits may be varied to compensate for any diflierencc in the characteristics of the two electronic valves whereby the output circuits may be maintained in balanced relation with respect to the carrier frequency oscillations.

A source of modulating signal current va-. riations such as, for example a transmitter 6 and a battery 7, is coupled to the valve input circuits by means'of a transformer 8.

The transformer 8 is provided with a. grounded case 9 to whichthe transformer core is connected. This construction stabi- 'zqueucy oscillations. two windings o'l retardation coilv 10 connected in the respective individual. paths of the valve input circuits li etvvceu the sources of high frequency oscillations and modulating signal current vari These tvvo windings, Which have a coininon core, are connected. so as to he pa 'allel aiding to the high. tlirequency oscillations and. series opposing to the modulating nal current variations.

l l ith: respect to the coil it). the

parallel ai 4; refers to the H currents supplied 'roni the sec Ollfillilij" winding-oft transito." the Windu l a ct th alte rn atint nor a),

ings of coil 10 provide parallel pa to ground: through the (listrilnited capaci v oi lll'fillSlOZ-flllfil 8. i For such cliirrcnts, the u'iiuh ings of coil 10 are no aranged as to set up magnetic fields Which tendv to produce in. the core. on. a plane intersecting the core inter-- mediate the wiiulings magnetic po which areoff opposite signs. The fields may therefore he said to he inutuallv airline.

ll (12. such currents, the coil 10 is accordino ly highly inductive and offers high in'ipeoauce.

Tlhe term series opposing applied to coil 10 refers to the fact thrt current from the transformer ll lows in sei .s through the windings of? coil 10, that is, at any given instant in one direction through one road inc and in the opposite direction through the other wiudinox The flow oi this current tlnrough the WllHl'lHQS oi coil l0 causes netic :tielt to he set up in the core such that there tends to he produced. on a plane intersecting the core intermediate the Wind magnetic poles which are ot the same The fields may thcre'tore he dc :rihed as n'iutually opposing. For such cu cuts. the coil 10 is suhstantially noninductive and otters low in'ipedancc.

These windings of the retardation coil therefore oller very lOW impedance to the modulating signal variations, hut oiler such high in'ipedance to the high frequency oscillations as to etl'ectivel c prev of suchoscillations. Conseqiientl the toll force of the high frequency, oscillations is impressed upon the control electrrules of valves irrespective of the presence of capacity front the transformer 53 to go a A; negative polarizing potential for eeieoea control electrodes of the valves is snm'ilieil from a battery ll. or other source.

The output (1 rcuits of the valves 1v and are connected in parallel with respect to a hatter 12.. arranged in. the common conductor of said circuits. l i-ach output circuit contains one hall oil? the priniiary winding of an output transformer1'3. The secondary win ding oi the output transformer 13 is connecteo to outgoing circuit. 1

i lorn'iallv. when no signal current varia tions are impressed upon circuit lt, the high frequency oscillations from source 4: acting t rough t. .ilornier 3' in'ipress equal. voltage variations 0'; the same phase upon the control electrodes oi the. valves, thereby producing equal fluctuations ot the same phase in the output circuits. Since the two halves oi the Pl'lil'lfil'j. winding ot the output transtoriner 13 are wo nd in the 3311M fCCtlOl], the outgoing circui 1.5 is differentially coupotential variations are augn'iented upon one control. electrode and decreased upon the other, producing coii'nesuiiondingly augmented it'lucl'l'iations in one output circuit and correspondingly reduced :tluctiuitions in? the other The :llimtuations in the output circuits are-no. longer hulanced and consequonu l}; oscillations are produced. in the outgoing cit. nit 15 which. have an amplitude pnoportiouatc to the instantaneous values of the low ttreqiuincy modulating currents iucoinrug from circuit 14-.

The halaiuJcd' modulator shown in the drawiigr constitutes a duplex translating apparatus wherein. the unimululatedcarrier oscillations as suppi-wised and the currents or? 'l'recpicncies 1in the side hands of the carrier are supplied to the outgoing circuit.

The modulator cinho ing the present in. vention is highly eliicieut iii that the optiinunr control electrode potential is maintunicilarilh onl approximately twenty per cent of the carrier frequency energy hereto'l ore required. i U

The invention set tl orth herein is oat course susceptible to various other embodiments and adaptatimis. A

The invention-clainicd is:

l. la "Wave transl. ionsystem, a repeater, a source oi? signals and: a source of carrier raves, individual means for couq'ilingsaid sources to said repeater. and means oliering a cumulati ini edance to waves from one source and a dilterential inr edanco to Waves from the other source included hetween said SQ llCGSr :2. A. translating apparatus comprising a Ill) duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths, conductive evacuated gaps in said individual paths, a source of high frequency oscillations associated with the common path, and, the individual paths, a source of modulating signal variations associated with the indi vidual paths, and means in the individual paths which is substantially non-inductive to current from one source and highly inductive to current from the other source to provide high impedance to the high frequency oscillations and low impedance to the modulating signal current variations.

3. A translating apparatus comprising a duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths, conductive evacuated gaps in said individual paths, a source of high frequency oscillations associated with the common path and the individual paths, a source of modulating signal current variations associated with the individual paths, and a retardation coil having two windings, one in each individual path, said windings being connected to be parallel aiding to the high frequency oscillations and series opposing to the modulating signal current variations.

4. A translating apparatus comprising a duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths, conductive evacuated gaps in said individual paths, a source of high frequency oscillations associated with the common path and the individual paths, a source of modulating signal current variations associated with the individual paths, and an inductive winding in each individual path with a common core therefor, said windings being arranged so as to offer high impedance to the high frequency oscillations and low impedance to the modulating signal current variations.

5. A. translating apparatus comprising a duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths. conductive evacuated gaps in said individual paths, a source of high frequency oscillations associated with the common path and the individual paths, a source of modulating signal current variations associated with the individual paths, and an inductive winding in each individual path between the two sources with a core common to the windings, said windings being connected so as to be parallel aiding to the high frequency oscillations and series opposing to the modulating signal current variations.

6. The combination of an electronic valve modulator having a grounded, heated cathode, an anode, and a control electrode, an input circuit connected to the cathode and control electrode, means to couple a source of modulating currents with the input circuit, said coupling means having a capacity to ground in parallel with the control elcctrode, a source of currents of higher frequency coupled to said input circuit, and in ductive means between said source of modulating currents and said source of currents of higher frequency which is also between said source of modulating currents and said input circuit. said inductive means being adapted to have a different inductance with respect to the currents from the said sources. 7. The combination ofan electronic valve modulator having a grounded heated cathode, an anode and a control electrode, an input circuit connected to the cathode and control electrode, means to couple a source of modulating currents to the input circuit, said coupling means having a capacity to ground in parallel with the control electrode, a source of carrier currents of high frequency coupled to the input circuit and means to prevent said capacity from shunting the carrier currents from the control electrode, including a choke coil comprising a plurality of windings upon a. toroidal magnetic core, said windings being arranged to be ineffective with respect to said modulating currents, and to be effective with respect to said carrier currents in magnetizing said core.

8. The combination of a modulator having two electronic valves, each having a grounded heated cathode, an anode and a control electrode, parallel input circuits for the valves including a common path connected to the cathodes and individual paths connected to the control electrodes, at source of high frequency oscillations associated with the common and individual paths, a source of modulating signal current variations associated with the individual paths, and means in the individual paths between said sources allowing the passage of the modulating signal current variations and preventing the passage of the high frequency oscillations, said means comprising a choke coil having a plurality of windings traversed by said high frequency oscillations in such manner as to offer cumulative impedance thereto.

9. A translating device having an element substantially at ground potential for high frequency currents, an input circuit for said device including means to impress thereon high frequency currents and means to impress thereon low frequency currents, and means comprisinga choke coil having two windings on a single core adapted to be inductive with respect to said high frequency currents to prevent the high frequency currents from being dissipated thru the capacity to ground of said low frequency impressing means.

10. In a wave translation system, a space discharge tube, a source of high frequency waves and a source of signal waves applied thereto, means for coupling said sources to said tuloerhaving a capacitive path tending to divert; high frequency energy from. said tubes, and means in series With said path comprising a two-Winding coil on' a single core oif'ering high impedance to high frequency Waves and low impedance to signal waves. a

11. In a Wave translation system, a plurality ofaspace discharge tubes, sources of signal Waves and high frequency Waves con nected to said tubes by means having a path including a capacity in shunt to the high frequency source tending co-reduce" the high -frequency voltage applied to said tubes, and means, in said path, which is non-inductive twee-pee for current from one of said sources but ofters high impedance to aves from said other source,

12; Int a Wave translation system, a plurality 01 space discharge tubesv in push-pull relation, a source of signals and a source of carrier wayes connected to said tubes, a transformer for saidsignal source which provides an: inherent capacity path in shunt to said carrier Wave source, said path including leads in a series circuit including said transformer and said tubes, and a choke coil connected to said leads in such manner asto he noninductive to signal Waves and inductive to carrier waves.

In Witness whereof, I hereunto subscribe my name thisQT day of March A. D, 1923.

FREDERICK C. WILLIS; 

